Carbon fluorides can be prepared by fluorinating various carbon powder materials, and are present as solid powders. Since carbon fluorides have an extremely low surface energy, and can exhibit their exellent characteristics under sever conditions regardless; of atmosphere, the carbon fluorides have been evaluated as excellent industrial materials in wide technical fields such as water- and oil-repellents, mold-releasing compounds, non-tackifying agents and solid lubricants.
When utilizing those excellent properties of the carbon fluorides, rather than that the carbon fluoride powder is used alone in the form of powder, the carbon fluorides are generally utilized, for example, usually in the manner of adding and dispersing the carbon fluoride particles into materials such as resins and rubbers, in the manner of dispersing into oils, greases, organic solvents or aqueous solutions, or in the manner of fine particle composits with other powders.
However, when utilizing the above excellent various properties by composing the carbon fluoride powder with other materials, there is a problem that, since it is difficult to disperse the carbon fluoride powder in the other materials uniformly and stable with other materials, the desired properties cannot be sufficiently obtained.
The reasons are in that, since commercially available, common, and conventional carbon fluoride particles are highly fluorinated throughout the inner portion to provide particles which are wholely in the form of (carbon fluoride, (1) the specific gravity becomes higher to about 2.5 to 3.0, and (2) during the fluorinating step, the particles are broken irregularly due to stress yielded in the whole particle to make the particle size distribution very wide and to make the particle shape irregular, because though a spacing of (001) plane of microcrystal of graphite is 0.34 nm, a spacing of the plane of carbon fluoride widens to about 0.6 to 0.9 nm due to the fluorination. Therefore, the wholely fluorinated carbon fluoride is inferior in dispersibility and powder flowability.
If carbon fluoride particles having a low specific gravity and a narrow particle size distribution can be obtained, such carbon fluoride particles are advantageous in view that a difference of specific gravity from a dispersing medium is made small to improve the dispersibility. For example, as carbon fluoride particles which may have a low specific gravity, JP-A-142958/1975 discloses carbon fluoride particles having a fluorine content of 35 to 55% by weight (corresponding to an atomic ratio of fluorine atom to carbon atom (hereinafter referred to as "F/C") of 0.34 to 0.77).
However, the carbon fluoride particles having such a high F/C within the above range are in such a state that the spacing of (001) plane of the crystal is maximum, and thus, as mentioned above, the particles tend to be broken. Therefore, when dispersing into other materials, there remains a problem as to dispersibility, and the excellent lubrication property cannot be exhibited.
Also, it is known that modified carbon materials for composite materials prepared by treating the carbon surface with a fluorine gas at -80.degree. to 50.degree. C. (JP-B-38686/1992). However, there is not yielded any carbon fluoride on the surface of the material, but is only yeilded a weak, semi-ionic C-F bond which contributes to hydrophilic property. Accordingly, the treated carbon fluoride does not exhibit a water-repelling property which is owned by the carbon fluoride, rather becomes more hydrophilic than the starting carbon material (Proceedings of 16th Fluorine Chemistry Conference, p16 (Sep. 20, 1991), 17th Proceedings of Fluorine Chemistry Conference p21-22 (Sep. 21, 1992)).
There is a graphite material for an atomic reactor, which comprises a carbon fluoride at a part or all of its surface region or of pores of surface layer (JP-B-31283/1981). This art directs to graphite molding, and is technically different from carbon fluoride which is used in the manner of additives to other materials.
The present invention has been completed from those viewpoints, and one object is to provide novel carbon fluoride particles having an excellent dispersibility and powder flowability and further a controlable conductivity and charging property which are not owned by the conventional carbon fluoride particles, as well as a water-repelling property, oil-repelling property, lubricating property, non-adhesion, non-wetting property and stain resistant which are owned by the conventional carbon fluoride perticles, said carbon fluoride particles being carbon fluoride particles with a low specific gravity in which the F/C as a whole is maintained at a low level but the F/C at the particle surface is high.
An object of the present invention is to provide a process for preparing the novel carbon fluoride particles in which a consuming amount of expensive fluorine gas can be reduced.
An object of the present invention is to provide, as applications of the novel carbon fluoride, a water- and oil-repellent, a non-tackifying agent, a solid lubricant and an agent for imparting electric concuctivity.
Another object of the present invention is to provide a composite material which is composed with various other materials in various manners.
Another object of the present invention is to provide an additive to toners which gives excellent effects that an amount of toners adhered to the carrier surface for developing electrostatic emage can be reduced and that a cleaning property of the toners remaining on a surface of a photoreceptor can be improved.
Further object of the present invention is to provide an additive to carrier coating in order to produce a carrier for developing electrostatic image, which is excellent in abrasion resistance and toner-spent property and does not yield irregularity in toner charge.
An object of the present invention is to provide a fixing roller for developing electrostatic image, which does not cause both the hot offset and electrostatic offset.
An object of the present invention is to provide a gas diffusion electrode for a phosphoric acid fuel cell or an air battery, which has a small internal resistance and a long life.
An object of the present invention is to provide an alkaline battery using a hydrogen-absorbing alloy, which is excellent in rapid charging and has a long durability.